Method for activating the lipid catabolic metabolism in enteric epithelium and improving the lipid metabolism in enteric epithelium

ABSTRACT

Disclosed are a method for activating lipid metabolism in the small intestine epithelium and also a method for promoting accumulation of fatty acids into the small intestine epithelium, each of which features administering an effective amount of a diacylglycerol. Also disclosed are methods for improving various symptoms in diabetes, which have ingesting a diacylglycerol. Ingestion of the diacylglycerol leads to α-cumulation of the fatty acids in the small intestine. The fatty acids so accumulated promote induction of β-oxidation, thereby not only activating lipid catabolism but also making it difficult to allow lipids to accumulate as triacylglycerols. This series of actions eventually results in development of lowering action for blood remnant-like lipoprotein level and also lowering action for blood leptin level, and hence, lipid metabolism is improved. Further, energy consumption is enhanced by promoting the induction of β-oxidation and activating lipid catabolism.

BACKGROUND OF THE INVENTION

This invention relates to a method for promoting accumulation of fattyacids into the small intestinal epithelium, and also to a method forimproving lipid metabolism in the small intestine epithelium for thesuppression of triacylglycerol synthesis, the enhancement ofβ-oxidation, the enhancement of uncoupling protein (UCP) expression, thepromotion of energy consumption, the lowering of blood leptin level, thelowering of blood remnant level and/or the like purpose. This inventionis also concerned with a method for treating diabetes and a method forimproving lipid metabolism in a diabetic patient by ingestingdiacylglycerol.

DESCRIPTION OF THE BACKGROUND

From research in recent years, elucidations have been made increasinglyas to a connection between lipid metabolism disorders, such as anincrease in blood leptin level and an increase in blood remnant level,and diseases such as angina pectoris, myocardial infarction, cerebralthrombosis, cerebral infarction and aortic aneurysm.

It is, therefore, desired to lower the remnant and leptin levels byimproving lipid metabolism (Fertil Steril 2002 March; 77 (3), 433-44).

Remnant-like lipoprotein particles (RLP; called “remnant particles” orsimply “remnant”) have been reported to be a strong risk factor for theabove-described diseases, because they are susceptible to absorptioninto blood vessel walls and cholesterol in RLP so absorbed accumulatesin the blood vessel walls. Leptin, which is a hormone secreted mainlyfrom adipose tissues, on the other hand, has been reported to performcontrol on body fat and serum lipids by promoting energy consumption,through burning promoting effect for body fat. If lipid metabolismdisorders continue, however, the serum leptin level increases and leptincan no longer exhibit its inherent effect. If this situation arises, itis necessary to lower the serum leptin level such that leptin cansmoothly perform its function.

It is, therefore, very important for the prevention and treatment ofdiseases, which are associated with lipid metabolism, to lower bloodremnant level and blood leptin level and also to promote energyconsumption.

In general, lipids (triacylglycerols) ingested as a meal are degraded bylipase into fatty acids and 2-monoacylglycerol in the small intestine,and subsequently, most of the fatty acids and 2-monoacylglycerols areusually resynthesized into the triacylglycerols in the small intestineepithelium, followed by a move into blood. A portion of the fatty acidsso formed, on the other hand, is subjected to catabolism in the smallintestine epithelium and is converted into energy. In other words, theenergy of the fatty acids is converted into an electrochemical potentialof protons within mitochondria through a series of pathways such asβ-oxidation and electron transport systems.

It is a function of an uncoupling protein (UCP) to uncouple oxidativephosphorylation. Described specifically, the electron transport systemand ATP synthesis are closely coupled with each other by a protongradient across mitochondrial inner membranes, and UCP is a specialchannel which eliminates this proton gradient in a short-cut manner.When UCP is activated, chemical energy of an oxidized substrate isconverted into heat instead of being employed for ATP synthesis(“Seikagaku (Biochemistry)”, 70, 212-216, 1998; “Rinsho Kagaku (ClinicalScience)”, 34, 1043-1048, 1998). Accordingly, a functional disorder ofUCP and lowering in its expression are considered to decrease energyconsumption and to lead to accumulation of energy and obesity.Conversely, an increase in the expression of UCP and its activation areconsidered to increase energy consumption and to result in anti-obesity.

It is also known that the small intestine is a tissue active in theexpression of UCP, that the expression of small intestine UCP variesdepending on dietary lipids, and that the expression of small intestineUCP is increased especially by fish oil having lipid metabolismimproving effect. In view of these, small intestine UCP is suggested toplay an important role in lipid metabolism (Biochem J., 345, 161-179,2000; Biochimica et Biophysica Acta, 1530, 15-22, 2001)

The β-oxidation system is a principal metabolic degradation pathway forfatty acids. A group of enzymes, such as MCAD (medium-chain acyl-CoAdehydrogenase) and ACO (acyl-CoA oxidase), play parts in the β-oxidationpathway. The β-oxidation system plays an important role not only in thedegradation of fatty acids but also in thermogenesis through conversionof fatty acids into energy. Deficit of β-oxidation enzyme has beenreported to lead to a reduction in energy expenditure (J. Clin. Invest.,102, 1724-1731, 1998). Therefore, enhancement of β-oxidation isconsidered to improve lipid metabolism and energy metabolism and also tolead to an improvement in hyperleptinemia.

PPAR (peroxisome proliferator activated receptor) is a transcriptionfactor which controls development of UCP and β-oxidation relatedmolecules (acyl-CoA oxidase, medium chain acyl CoA dehydrogenase, etc.).Participation of fatty acids in the activation of PPAR is known wellfrom experiments on cell level. As has been described above, oil(triacylglycerols) is generally degraded into 2-monoacylglycerols andfatty acids in the small intestinal tract, and subsequent to absorption,the 2-monoacylglycerols and fatty acids are resynthesized intotriacylglycerols in the small intestine epithelium. The presentinventors, therefore, postulated that, if it is possible to cause fattyacids to accumulate in the small intestine epithelium and to increaseits concentration there, level/expression of β-oxidation relatedmolecules and UCP would be increased. Under this postulation, thepresent inventors have proceeded with research. No specific method hasbeen proposed yet to date for storing fatty acids in cells.

An object of the present invention is to provide a method for promotingaccumulation of fatty acids into the small intestine epithelium. Anotherobject of the present invention is to provide a method for improvinglipid metabolism for the suppression of triacylglycerol synthesis, theenhancement of β-oxidation, the enhancement of uncoupling protein (UCP)expression, the promotion of energy consumption, the lowering of bloodleptin level, the lowering of blood remnant level and/or the likepurpose. A further object of the present invention is to provide amethod for activating lipid catabolism in the small intestine.

Diacylglycerols are used for foods, as they have unique functionswithout side effects. Specifically, cholesterol level lowering agents(JP 63-104917 A), body weight gain suppressants (JP 4-300826 A),general-purpose oil compositions (U.S. Pat. No. 6,004,611), oil or fatcompositions (WO 01/13733), vegetable-sterol-containing oil or fatcompositions (WO 99/48378), body fat burning promoters (JP 2001-64672A), and the like have been proposed.

Nonetheless, absolutely nothing is known as to what effectsdiacylglycerols exhibit in the small intestine.

In recent years, multiple risk factor syndrome called visceral fatsyndrome, syndrome X or the death quartet, which is caused as a resultof complication of certain factors such as obesity, hyperlipemia andhypertention in addition to diabetes, is attracting attention as a causeof cardiovascular disease. It has been reported that concerningdiabetics, morbidity rate and mortality rate become higher upon onset ofcomplications such as cardiovascular diseases. The onset rate of greatvessel injuries (such as myocardial infarction) among diabetics ishigher compared with that among those not suffering from diabetes. Ascauses of this tendency, the principal one is lipid metabolic disorder.For example, small dense LDL of the same particle size LDL cholesteroltends to occur in diabetics and acts as a cause of arteriosclerosis.

Further, type II diabetes which accounts for 90% or higher of diabetesis considered to be a state in which high blood sugar level has beendeveloped by occurrence of reductions in the effects of insulin as aresult of complication of a reduction in the secretion of insulin fromthe β cells of the pancreas and a reduction in insulin sensitivity(insulin resistance) at skeletal muscle, the liver and adipose tissue,which are insulin's target organs, to various extents. On the otherhand, obesity caused by environmental factors such as binge eating, highfat diet and insufficient exercise is considered to take substantialpart in insulin resistance together with genetic diathesis. Theexistence of obesity-associated insulin resistance leads, as its cost,to hyperinsulinemia. To insulin resistance caused by obesity, the bodyresponds by excessively secreting insulin. When such a state (insulinresistance) continues, the β cells of the pancreas exhaust so that theinsulin secreting ability gradually drops to eventually result indiabetes conditions (high blood sugar). When this high blood sugar statecontinues, glucose itself increases secretion of insulin from the βcells of the pancreas and insulin resistance at peripheries, and hence,glucose toxicity is exhibited. A vicious circle is now formed, leadingto further deteriorations in conditions.

Basic curing or treatment methods for diabetes are kinesiologicaltherapy and dietary therapy. If the blood sugar level cannot becontrolled by these methods alone, pharmacotherapy is then relied upon.It is important not only to control the blood sugar level but also toimprove diabetes while taking complications into consideration.Accordingly, a pharmaceutical which can improve insulin resistance isbelieved to be extremely useful as a remedy for diabetes.

Another object of the present invention is, therefore, to provide amethod for improving various factors of a diabetic, for example, sugarblood level, insulin resistance and lipid metabolic disorder.

SUMMARY OF THE INVENTION

The present inventor, therefore, conducted various investigations with aview to elucidating effects of diacylglycerols in the small intestine,especially in the small intestine epithelium. As a result, it has beenfound that diacylglycerols are degraded in the cavity of the smallintestinal tract and subsequent to absorption in the small intestineepithelium, the resulting fatty acids are hardly reconstituted intotriacylglycerols and accumulated there, and also that the thus-formedfatty acids induce the expression of genes involved in lipid metabolismin the small intestine and suppress synthesis of triacylglycerols. Inother words, the present inventors have found that diacylglycerols havethe lipid catabolism activating effect in the small intestine and lipidmetabolism improving effect.

The present inventors also conducted further investigations on effectsof diacylglycerols on diabetes model animals and the blood sugar leveland insulin resistance in human, and effects of diacylglycerols on serumlipids in diabetics. As a result, it has been found that, when adiacylglycerol is ingested, the blood sugar level is lowered and theinsulin resistance is improved. In addition, the ingestion of adiacylglycerol has also been found to reduce lipid metabolic disordersin a diabetic, for example, the serum triacylglycerol level, theconcentration of triacylglycerols in VLDL fraction, the concentration oftriacylglycerols in LDL fraction, and the concentration oftriacylglycerols in small dense LDL fractions. Furthermore, theingestion of a diacylglycerol has also been found to lower HOMA-R, whichis an index of insulin resistance in a diabetic patient.

In one aspect of the present invention, there is thus provided a methodfor activating lipid catabolism in the small intestine epithelium, whichcomprises administering an effective amount of a diacylglycerol.

In another aspect of the present invention, there is also provided amethod for promoting accumulation of fatty acids into the smallintestine epithelium, which comprises administering an effective amountof a diacylglycerol.

In a further aspect of the present invention, there is also provided amethod for inducing expression of a small intestine lipid metabolicgene, which comprises administering an effective amount of adiacylglycerol.

In a still further aspect of the present invention, there is alsoprovided a method for suppressing synthesis of a triacylglycerol in thesmall intestine epithelium, which comprises administering an effectiveamount of a diacylglycerol.

In a still further aspect of the present invention, there is alsoprovided a method for improving blood lipid metabolism, which comprisesadministering an effective amount of a diacylglycerol.

In a yet further aspect of the present invention, there is also provideda method for promoting energy consumption, which comprises administeringan effective amount of a diacylglycerol.

In a yet further aspect of the present invention, there is also provideda method for treating diabetes, which comprises administering aneffective amount of a diacylglycerol to a diabetic patient.

In a still yet further aspect of the present invention, there is alsoprovided a method for improving lipid metabolism in a diabetic patient,which comprises administering an effective amount of a diacylglycerol tothe diabetic.

In a still yet further aspect of the present invention, there is alsoprovided a dietotherapeutic method for a diabetic patient, whichcomprises administering an effective amount of a diacylglycerol.

In a still yet further aspect of the present invention, there is alsoprovided a medical food for a diabetic patient, which comprises adiacylglycerol.

In a still yet further aspect of the present invention, there is alsoprovided a processed oil or fat food having insulin resistance improvingeffect, comprising a diacylglycerol.

Ingestion of diacylglycerols results in the accumulation of fatty acidsin the small intestine. The fatty acids so accumulated promote inductionof a β-oxidation enzyme to activate lipid catabolism at the smallintestine, so that energy consumption is promoted and the fatty acidsare hardly resynthesized into triacylglycerols. Further, ingestion ofdiacylglycerols over an extended time promotes burning of not only thediacylglycerols but also triacylglycerols ingested through other meals,and therefore, accumulation of body fat is suppressed. In addition,blood remnant-like lipoprotein and leptin levels are lowered, and lipidmetabolism is improved.

Further, ingestion of a diacylglycerol by a diabetic leads not only to areduction in blood sugar level and an improvement in insulin resistancebut also to significant reductions in serum triacylglycerol level, theconcentration of triacylglycerols in VLDL fraction, the concentration oftriacylglycerols in small dense LDL fraction, the concentration oftriacylglycerols in LDL fraction and the like so that lipid metabolismis improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows variations in energy consumptions by rats, which ingesteddiacylglycerols (DAG) and triacylglycerols (TAG), respectively, in 22hours;

FIG. 2 illustrates variations in the concentrations of ¹³C—CO₂ inexpirations from mice, which ingested diacylglycerols (DAG) andtriacylglycerols (TAG), respectively, after administration of¹³C-tripalmitin;

FIGS. 3A and 3B depict percent accumulations of epididymal fat andpercent accumulations of mesenteric fat in mice which ingesteddiacylglycerols (DAG) and triacylglycerols (TAG), respectively;

FIG. 4 is a diagram showing blood sugar level lowering effect of adiacylglycerol on diet-induced diabetes model C57BL/6J mice; and

FIG. 5 is a diagram depicting blood sugar level lowering effect of adiacylglycerol on hereditary diabete model C57BL/KsJ-db/db mice.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Constituent fatty acids of the diacylglycerol for use in the presentinvention may preferably be those having carbon numbers of from 8 to 24,especially from 16 to 22. Among the entire constituent fatty acids ofthe diacylglycerol, the content of unsaturated fatty acids may bepreferably from 70 to 100 wt. % (hereinafter described simply as “%”),more preferably from 90 to 100%, particularly preferably from 93 to100%, most preferably from 95 to 100%. From the standpoint of furtherenhancing the lipid metabolism improving effect, the fatty acidaccumulation promoting effect and the diabetes treating effect, the(cis-form unsaturated)/(trans-form unsaturated+saturated) ratio may bepreferably 6 or greater, more preferably from 9 to 25, still morepreferably from 9 to 20. On the other hand, the particularly preferredcontent of the trans-form unsaturated fatty acids in the diacylglycerolmay be 5% or lower and the especially preferred content of the saturatedfatty acids may also be 5% or lower. From the standpoint of effects andoxidation stability, 15 to 90% of the constituent fatty acids compriseω3 unsaturated fatty acids, with 20 to 80% being more preferred, 30 to70% being still more preferred, and 40 to 65% being particularlypreferred. Examples of the ω3 unsaturated fatty acids can includeα-linolenic acid (C18:3), stearidonic acid (C18:4), eicosapentaenoicacid (C20:5), docosapentaenoic acid (C22:5) and docosahexaenoic acid(C22:6), with α-linolenic acid, eicosapentaenoic acid anddocosahexaenoic acid being preferred, and α-linolenic acid being morepreferred. Diacylglycerols include 1,3-diacylglycerols and1,2-diacylglycerols (2,3-diacylglycerols). More preferably, the weightratio of the 1,3-diacylglycerols to the 1,2-diacylglycerols may be 7:3.From the standpoint of enhancing the lipid metabolism improving effectand the diabetes treating effect, increasing the accumulation of fattyacids and improving the industrial productivity, the 1,3-diacylglycerolsmay amount preferably to 50% or more, more preferably to 55 to 100%,especially to 60 to 90% of the whole diacylglycerols.

The diacylglycerol for use in the present invention can be produced, forexample, by subjecting an oil or fat, which contains target constituentfatty acids, and glycerol to transesterification or by causing lipase toact on a mixture of the target constituent fatty acids or esters thereofand glycerol to conduct transesterification. From the standpoint ofavoiding isomerization during the reaction, the transesterificationmaking use of lipase is more preferred. In this transesterificationmaking use of lipase, it is preferred, for the prevention ofisomerization during a purification stage after completion of thereaction, to conduct the purification under such mild conditions that noisomerization of fatty acids would take place.

As is appreciated from the foregoing, it is preferred to use thediacylglycerol as an oil or fat composition which also containstriacylglycerols and the like. From the standpoint of effects, the oilor fat composition may contain preferably 15 to 100%, more preferably 40to 99%, particularly preferably 60 to 95%, most preferably 80 to 95% ofdiacylglycerols. Fatty acids formed from diacylglycerols as a result ofdegradation by lipase in the course of digestion are more prone toaccumulate in the small intestine epithelium than those formed fromtriacylglycerols. Use of an oil or fat composition containing 15% ormore of diacylglycerols can, therefore, bring about excellent lipidmetabolism improving effect. From the standpoint of the diabetestreating effect, it is also preferred to have diacylglycerols containedin a proportion of 15% or higher.

The oil or fat composition may contain triacylglycerols. From thestandpoint of effects, taste and flavor, and oxidation stability, thecontent of the triacylglycerols in the oil or fat composition may rangefrom 0 to 85%, preferably from 1 to 59.9%; more preferably from 5 to39.9%, most preferably from 5 to 19.9%. As constituent fatty acids ofthe triacylglycerol, unsaturated fatty acids having the carbon numbersof which range from 16 to 22 may be contained preferably in a proportionof from 55 to 100%, more preferably in a proportion of from 70 to 100%,especially in a proportion of from 80 to 100%, most preferably in aproportion of from 90 to 97%, from the standpoint of effects, taste andflavor, and texture. From the standpoint of oxidation stability, ω3unsaturated fatty acids may also be contained, as constituent fattyacids of triacylglycerols, preferably in a proportion of from 0 to 40%,more preferably in a proportion of from 0 to 30%, particularly in aproportion of from 0 to 20%, most preferably from 0 to 15%.

The oil or fat composition may also contain monoacylglycerols. From thestandpoint of taste and flavor and oxidation stability, their contentmay be 0 to 30%, preferably 0.1 to 10%, more preferably 0.1 to 5%,especially preferably 0.1 to 2%, most preferably 0.1 to 1.5%.Constituent fatty acids of the monoacylglycerols may preferably the sameas those of the diacylglycerols from the viewpoint of manufacture.

Free fatty acids contained in the oil or fat composition have anoffensive taste and from the standpoint of taste, their content may beset below 10%, preferably below 5%, more preferably below 2.5%,especially preferably below 1%, most preferably below 0.5%.

Preferably, an antioxidant can be added to the oil or fat composition toimprove its oxidation stability. Examples of the antioxidant can includebutylhydroxyanisole (BHA), butylhydroxytoluene (BHT), vitamin A, vitaminC, vitamin E, phospholipids, polyphenol, and tert-butylhydroquinone(TBHQ). Two or more of these antioxidants canal so be used incombination. The antioxidant may be contained preferably in a proportionof from 0.005 to 0.2%, especially in a proportion of from 0.04 to 0.1%in the oil or fat composition.

It is also preferred to further add a crystallization inhibitor to theoil or fat composition. Examples of crystallization inhibitors usable inthe present invention can include polyol fatty acid esters such aspolyglycerol condensed licinoleic acid esters, polyglycerol fatty acidesters, sucrose fatty acid esters, sorbitan fatty acid esters,polyoxyethylene sorbitan fatty acid esters and propylene glycol fattyacid esters. Two or more of these crystallization inhibitors can also beused in combination.

The crystallization inhibitor may be contained preferably in aproportion of from 0.02 to 0.5%, more preferably from 0.05 to 0.2% inthe oil or fat composition.

In vegetable oil, phytosterols are contained in a proportion of from0.05 to 1.2% or so. However, the content of phytosterols in an oil orfat composition differs depending on its production process. Use of afatty acid, which is available abundantly on the market and was obtainedby distillation, as a raw material, for example, results in an oil orfat composition in which the content of a phytosterol is low. In such acase, it is preferred to add phytosterols such that the oil or fatcomposition contains phytosterols in a total proportion of from 0.05- to20%, especially from 0.3 to 1.2%. Examples of such phytosterols caninclude free forms such as α-sitosterol, β-sitosterol, stigmasterol,campesterol, α-sitostanol, β-sitostanol, stigmastanol and campestanol;and ester forms such as their fatty acid esters, ferulic acid esters andcinnamic acid esters.

In the methods according to the present invention, the diacylglycerolcan be administered preferably at a daily dosage in a range of from 0.1to 25 g, especially from 0.1 to 20 g per adult, generally once toseveral times in a day. Administration of 0.1 g/day in terms of thediacylglycerol is essential for the development of the effects.

When the methods according to the present invention are applied for theprevention or treatment of a disease, illustrative dosage forms caninclude oral preparations, for example, solid preparations such aspowders, granules, capsules, pills and tablets, and liquid preparationssuch as solutions, suspensions and emulsions. These oral preparationscan each be produced by adding, in addition to the above-described oilor fat composition, one or more of excipients, disintegrators, binders,lubricants, surfactants, alcohols, water, water-soluble polymers,sweeteners, corrigents, acidifiers, and the like, which are commonlyemployed depending on the forms of oral preparations. When the oil orfat composition is used, its content in each orally administeredpharmaceutical may range generally from 0.05 to 100%, with 1 to 50%being particularly preferred, although the content varies depending onthe application purpose and preparation form of the medicine.

To ingest diacylglycerols in the form of foods in the methods accordingto the present invention, processed oil or fat foods containing thediacylglycerols can be used. For example, diacylglycerols can beformulated into health foods, functional foods, foods for specifiedhealth use, medical foods or the like, which exhibit specific functionsto promote health. Specific examples can include capsules, tablets andgranules; bakery foods such as breads, cakes, cookies, pies, bar cookiesand bakery mixes; salad dressings such as French dressing; oil-in-wateremulsion foods such as mayonnaise; water-in-oil emulsion foods such asmargarine and margarine-like spreads; confectioneries such as creams,chocolate and potato chips, ice cream and dessert; drinks; soups;sauces; coffee whitener; whipped cream; barbecue sauce; peanut butter;frying shortening; baking shortening; processed meat products; frozenfoods; powdered foods; meal replacers; and food materials such ascooking oils useful for tempura, fries and frizzled dishes. These foodscan each be produced by adding, in addition to an oil or fatcomposition, one or more food materials commonly employed depending onthe kind of the food. The content of the oil or fat composition in eachof these foods may range generally from 0.05 to 100%, particularlypreferably from 0.5 to 80%, although it differs depending on the kind ofthe food.

A description will hereinafter be made about processed oil or fat foodsaccording to the present invention, each of which contains adiacylglycerol. The term “processed oil or fat food” as used hereinmeans a food obtained by mixing an oil or fat composition, whichcontains 15% or more of a diacylglycerol, with one or more other foodmaterials or ingredients and then processing the resulting mixture. Foodraw materials or ingredients usable in such processed oil or fat foodscan include:

-   (1) Edible oils or fats

No particular limitation is imposed on an edible oil or fat for use inthe present invention insofar as it is a common edible oil or fat.Examples can include natural, animal or vegetable oils or fats andprocessed oils or fats obtained by subjecting them to ester interchange,hydrogenation, fractionation or the like. Preferred usable examples caninclude vegetable oils such as soybean oil, rapeseed oil, cottonseedoil, rice bran oil, corn oil, sunflower oil, palm oil, palm karnel oiland coconut oil; and their processed oils and fats.

-   (2) Emulsifiers

No particular limitation is imposed on emulsifiers in so far as they arecommonly used in foods. Illustrative are sugar fatty acid esters,sorbitol fatty acid esters, glycerol fatty acid esters, lecithin anddegradation products thereof, egg proteins, soybean proteins, milkproteins, and various proteins, peptides and the like obtained fromthese proteins by isolation or hydrolysis.

-   (3) Thickeners

No particular limitations are imposed on thickeners in so far as theyare commonly used in foods. Illustrative are polysaccharides such asxanthan gum, gellan gum, guar gum carageenan, pectin, tragacanth gum andvarious starches; and proteins such as gelatin and proteins.

-   (4) Various tasting agents such as common salt, sugar, vinegar, and    seasonings.-   (5) Various condiments such as spices and flavors.-   (6) Various food coloring matters.-   (7) Antioxidants such as tocopherol and natural antioxidant    ingredients.

Preferred illustrative formulas will hereinafter be described. Itshould, however, be borne in mind that they by no means limit use of thepresent invention.

a) Acidic Oil-in-Water Type Oil or Fat Processed Foods

-   -   Oil phase/water phase: 20/80 to 80/20 (preferably 30/70 to        70/30).    -   Amount of diacylglycerol: 15% or higher based on the oil or fat        in an oil phase (preferably 40% or more, notably 80% or more).    -   Amount of phytosterol: 0.05% or more based on the oil or fat in        an oil phase.    -   Amount of emulsifier: 0.05 to 5%.    -   pH: 2 to 6.

The pH is adjusted with vinegar, an organic acid such as citric acid ora salt thereof, or an acidifier such as lemon juice. Using theabove-described raw materials or ingredients, acidic oil-in-water typeoil or fat processed foods such as salad dressings and mayonnaise, whichhave insulin resistance improving effect and diabetes improving effect,can be prepared by methods known per se in the art. <Illustrativeformula> Mayonnaise Parts by weight Water phase Common salt 3.0 Sugar1.0 Seasoning (sodium glutamate) 0.5 Spice (mustard powder) 0.3 Egg yolk14 Vinegar (acidity: 10%) 8 Thickener 0.5 Water 22.7 Oil phase Oilcomposition I 50b) Plastic Water-in-Oil Type Oil or Fat Processed Foods

-   -   Water phase/oil phase: 15/85 to 85/15 (preferably 20/80 to        50/50).    -   Amount of phytosterol: 15% or more (preferably 40% or more,        notably 50% or more) based on the oil or fat in an oil phase.    -   Amount of phytosterol: 0.05% or more based on the oil or fat in        an oil phase.

Using the above-described materials or ingredients, plastic water-in-oiltype oil or fat processed foods such as margarine and margarine-likespreads, which have insulin resistance improving effect and diabetesimproving effect, can be prepared by methods known per se in the art.<Illustrative formula> Margarine-like spread Parts by weight Oil phaseOil or fat* 69.3 Lecithin 0.1 Monoacylglycerol 0.5 Flavor 0.1 Waterphase Water 28.4 Skim milk 0.3 Common salt 1.3*Oil composition I - 70% partially hydrogenated palm oil (IV = 40): 30%(melting point: 36° C.).c) Bakery Foods

-   -   Amount of oil or fat: 10 to 40%.    -   Amount of diacylglycerol: 15% or more (preferably 40% or more,        notably 50% or more) based on the amount of the oil or fat in an        oil phase.    -   Amount of phytosterol: 0.05% or more based on the the amount of        the oil or fat in the oil phase.    -   Wheat flour: 20 to 65%.    -   Sugar: 5 to 30%    -   Whole egg: 0 to 20%.    -   Common salt: 0.1 to 2%    -   Baking powder: 0 to 1%

Using the above-described raw materials or ingredients, bakery foodssuch as shortbread (bar cookies) and brioche, which have insulinresistance improving effect and diabetes improving effect, can beprepared by methods known per se in the art. <Illustrative formula>Shortbread (bar cookies) Parts by weight Wheat flour 60 Oil compositionI 10 Sugar 24.6 Common salt 0.4 Whole egg 5

Administration of diacylglycerols or an oil or fat composition withdiacylglycerols contained therein accelerates the accumulation of fattyacids in the small intestine epithelium. Further, the expression of thegene of β-oxidation enzymes and the gene of UCP, each of which takespart in the metabolism of lipids in the small intestine, is promoted.Furthermore, the synthesis of triacylglycerols in the small intestineepithelium is suppressed.

By these effects for promoting the accumulation of fatty acids in thesmall intestine epithelium and activating lipid catabolism, energyconsumption is enhanced. Further, continued ingestion of diacylglycerolor an oil or fat composition with diacylglycerol contained thereinfacilitates burning not only of the diacylglycerol itself but also oflipids ingested as meals and also suppresses their accumulation as bodyfat.

In addition, as a result of activation of lipid metabolism in the smallintestine epithelium by the methods of the present invention, PLLP-C,which is determined by quantitating blood RLP with cholesterol(Nakajima, K., Clin. Chim. Acta, 223, 53-71, 1993), and blood leptinlevel are lowered.

Further, ingestion of diacylglycerols or an oil or fat composition withdiacylglycerols contained therein by a diabetic patient, especially atype II diabetic patient leads to a reduction in blood sugar level andan improvement in insulin resistance. In particular, HOMA-R, an index ofinsulin resistance, drops significantly. Moreover, ingestion ofdiacylglycerols or an oil or fat composition with diacylglycerolscontained therein by a diabetic patient, especially a type II diabeticpatient also leads reductions in serum triacylglycerol level and in theconcentrations of triacylglycerols in lipoprotein fractions such asVLDL, LDL and small dense LDL.

The amount of diacylglycerols to be ingested by a diabetic patient maybe in a range of from 0.1 to 25 g, especially from 0.1 to 20 g peradult. It is preferred to divide this amount into 1 to several portionsin a day. The period of ingestion may be at least 1 week, preferably atleast 2 weeks, more preferably at least 3 weeks, still more preferablyat least 1 month, especially at least 2 months, most preferably at least3 months. To allow a diabetic patient to ingest diacylglycerols for sucha long period as described above, it is preferred to prepare medicalfoods for diabetes, in each of which diacylglycerols are used in placeof a portion or the entire portion of triacylglycerols, and to allow himor her to ingest them.

EXAMPLES

Examples will hereinafter be described. It is, however, to be borne inmind that the present invention shall not be limited the followingExamples.

The following oil compositions were prepared in accordance with thebelow-described procedure.

Oil or Fat Composition A

Fatty acids, which had been obtained by hydrolyzing commercial soybeanoil the trans acid content of which was 0.8%, were subjected towintering to lower the content of saturated fatty acids. Usingcommercial immobilized 1,3-position-selective lipase (“Lipozyme 3A”,trade name; product of Novo-Nordisk Industries A.S.) as a catalyst,those fatty acids and glycerol were subjected to esterification at 40°C. After the lipase preparation was filtered off, the reactant waspurified by molecular distillation to obtain an oil or fat compositionA.

Oil or Fat Composition B

Fatty acids, which had been obtained by hydrolyzing commercial rapeseedoil the trans acid content of which was 0.6%, and glycerol weresubjected to esterification at 40° C. by using “Lipozyme 3A”. After thelipase preparation was filtered off, the reactant was purified bymolecular distillation to obtain an oil or fat composition B.

Oil or Fat Composition C

Fatty acids, which had been obtained by hydrolyzing commercial rapeseedoil the trans acid content of which was 2.8%, and glycerol weresubjected to esterification at 40° C. by using “Lipozyme 3A”. After thelipase preparation was filtered off, the reactant was purified bymolecular distillation to obtain an oil or fat composition C.

Oil or Fat Composition D

Commercial high docosahexaenoic acid oil and glycerol were mixedtogether, and subjected to transesterification at 100° C. under reducedpressure by using an alkali catalyst (sodium methoxide). After thecatalyst was filtered off, the reactant was purified by moleculardistillation to obtain an oil or fat composition D.

Oil or Fat Composition E

Linseed oil fatty acids and glycerol were subjected to esterification at40° C. by using “Lipozyme IM” (trade name; product of Novo-NordiskIndustries A.S.). After the lipase preparation was filtered off,molecular distillation was conducted at 215° C. Subsequent to waterwashing, deodorization was performed at 215° C. for 2 hours to obtain anoil or fat composition E.

The acylglycerol compositions and diacylglycerol-constituent fatty acidcompositions of the thus-produced oil or fat compositions (A-E) andsoybean oil were analyzed by the below-described methods. The resultsare shown in Tables 1 and 2.

[Determination of the Acylglycerol Compositions]

Each oil was trimethyl silylated with a silylating agent (“SilylatingAgent TH”; trade name; product of Kanto Kagaku K.K.), and using acapillary column (“DBTM-1”, trade name; product of J & W ScientificInc.), the trimethyl silylated oil was then analyzed by gaschromatography.

[Determination of the Diacylglycerol-Constituent Fatty AcidCompositions]

Diacylglycerol fractions in each oil were collected by columnchromatography [after triacylglycerol fractions had been eluted using“Wako Gel C-200”, trade name; product of Wako Pure Chemical Industries,Ltd.) and hexane, the diacylglycerol fractions were obtained with a70:30 mixed solvent of hexane and ethyl ether]. Subsequent to methylesterification by a method known per se in the art, an analysis wasperformed by gas chromatography equipped with a capillary column(“CP-SIL88”, trade name; product of Chrompack Inc.). TABLE 1Acylglycerol Compositions (%) Oil or fat Monoacyl- DiacylglycerolsTriacyl- Phyto- composition glycerols (% of 1,3-DG) glycerols sterols A1.1 85.7 (59.9) 12.7 0.5 B 0.9 85.0 (59.5) 13.2 0.9 C 1.5 80.8 (56.5)16.7 1.0 D 0.9 53.1 (37.0) 45.8 0.2 E 1.0 84.8 (59.3) 14.0 0.2 Soybeanoil ND 1.0 98.7 0.3ND: Not detected

TABLE 2 Fatty Acid Compositions (%) Oil or fat composition CommercialConstituent fatty acids A B C D E soybean oil C14 — — — 1.6 — — C16 1.33.8 4.2 9.3 5.3 10.8 C16:1 — — — 3.4 — — C18 1.2 2.8 1.7 2.7 3.3 4.2C18:1 26.9 65.2 58.0 11.0 18.7 24.4 Cis 26.9 65.2 56.3 NT 18.7 24.4Trans 0.0 0.0 1.7 NT — 0.0 C18:2 60.7 17.8 24.3 1.4 15.4 51.6 Cis 59.717.4 21.0 NT 15.4 51.3 Trans 1.0 0.4 3.3 NT — 0.3 C18:3 7.8 9.0 8.7 0.755.2 7.2 Cis 6.6 6.7 7.1 NT 52.8 6.7 Trans 1.2 1.2 1.6 NT 2.4 0.5 C200.0 0.5 1.2 — — 0.4 C20:1 — — — 1.6 — — C20:5 — — — 6.6 — — C22:1 — — —1.1 — — C22:6 — — — 45.7 — — Uk 1.0 2.0 1.9 14.9 0.8 1.4 Trans 2.2 1.66.6 NT 2.4 0.8 Saturated 2.5 7.1 7.1 13.6 8.6 15.4 Trans + saturated 4.78.7 13.7 — 11.0 16.2 Cis 94.3 89.3 84.4 — 86.9 82.4 Cis/(trans +saturated) 20.1 11.3 6.2 NT 7.9 5.1uk: Unknown component,NT: Not tested.

Example 1 Small Intestine Perfusion Test

The following test was conducted in accordance with the method describedin J. Lipid Res., 39, 963 (1998).

Under anesthesia, Wistar rats (male, 6 weeks old) were each incised atthe abdomen, and a cannula (“PE50”, trade name; product of Clay Adams,Inc.) was arranged right underneath the pylorus. By a restraint gauge,an emulsion of triacylglycerols or diacylglycerols (triacylglycerols ofdiacylglycerols calculated as fatty acids: 90 mM, sodium chloride: 0.15M, 10 mM tris-HCl buffer: q.s. to pH 7.0, taurocholic acid: 10 mM) wasperfused at a rate of 4.5 mL/hr (Experiment 1). Five hours later, theperfusing was stopped, and 1 mL of RI-labeled fatty acids was promptlyinjected together with the emulsion of triacylglycerolsordiacylglycerols (Experiment 2). Namely, Experiment 1 was conductedsuch that the final concentration of [carboxy-¹⁴C]TO (triolein) or1,3-[carboxy-¹⁴C]DO (diolein) reached 3.2×10⁶ dpm/mL, while Experiment 2was conducted such that the final concentration of [1-¹⁴C]linoleic acidreached 1.6×10⁶ dpm/mL. Subsequently, the above-described emulsion oftriacylglycerols or diacylglycerols was injected again at the rate of4.5 mL/hr. Five minutes later, Nembutal was injected into the abdominalcavity, the small intestine (40 cm from the pylorus) was sampled andplaced in ice-cold 0.15M sodium chloride. It took 5 minutes from thecompletion of the injection of the labeled substance until the samplingof the small intestine in the ice-cold saline. After the small intestinewas cut into four equal parts and were then opened, the small intestinewas washed with 0.15 M sodium chloride (once), 0.2% Triton-X100 (once),and 0.15 M sodium chloride (twice). The mucosa of the small intestinewas scraped off and homogenized by a glass/Teflon® homogenizer in 0.15 Msodium chloride (10 mL). From 1 mL of the mucosa homogenate, lipids wereextracted by the Folch partition method. The thus-obtained lipids weredeveloped on a TLC plate (hexane:diethyl ether:acetic acid=80:20:1(v/v/v, chloroform:acetone=96:4 (v/v), and measurements were conductedto determine the quantities of the label absorbed in FFA,1,3-diacylglycerols, 1,2-diacylglycerols and triacylglycerols,respectively. The test results are shown in Table 3. TABLE 3Triacylglycerols Diacylglycerols Significant test Free fatty acids 100182 <0.05 1,3-Diacylglycerols 100 400 <0.001 1,2-Diacylglycerols 100 106— Triacylglycerols 100 94 <0.001Shown in terms of relative value when the amounts of the fatty acids andrespective acylglycerols existed during the perfusing oftriacylglycerols were each supposed to be 100.

When the diacylglycerols were perfused, the amounts of free acids and1,3-diacylglycerols existed in the mucosa of the small intestineepithelium were significantly high compared with the correspondingamounts when the triacylglycerols were perfused. On the other hand, nosignificant difference was observed in the amount of the1,2-diacylglycerol. In the diacylglycerol-administered group, the amountof triacylglycerols occurred as a result of re-synthesis in the smallintestine epithelium was significantly lower compared with that in thetriacylglycerol administration group.

Example 2 Induction of Small Intestine Lipid Metabolic Gene Expressionby the Ingestion of Diacylglycerols

Wistar rats (male, 7 weeks old) were each fed with an experimental feedwith 20% of a diacylglycerol-containing oil composition or soybean oilcontained therein and reared for 7 days. On the last day, those ratswere each dissected to sample the tissue of the small intestine. Fromthe tissue of the small intestine, RNA was isolated, and by Northernblotting, the expressed quantity of a lipid metabolism associated(β-oxidation) enzyme (MCAD: medium-chain acyl-CoA dehydrogenase) mRNAwas analyzed. The results are shown in Table 4. TABLE 4 Oil or fat Oilor fat Soybean oil composition B composition E MCAD mRNA 100 130 145Shown in terms of relative value when the expressed quantity of the MCADmRNA in the case of soybeans was supposed to be 100.

By the ingestion of the diacylglycerol-containing oil or fatcompositions B or E, the expression of the small intestine lipidmetabolic gene was promoted, and lipid metabolism was enhanced. Further,the diacylglycerol containing α-linolenic acid as a main constituentfatty acid activated the lipid metabolism system more strongly than thediacylglycerol containing linoleic acid or oleic acid as a mainconstituent fatty acid.

Example 3 Inhibition Test of Triacylglycerol Synthesis in the SmallIntestine Epithelium

Using FCS (fetal calf serum)-free, Dulbecco's modified Eagle's medium(D-MEM) with 5% FBS and 70 μg/mL kanamycin added therein, a ratsmall-intestine epithelial cell strain, IEC-6, was incubated under 5%CO₂ at 37° C. Individual fatty acids (oleic acid, linoleic acid,γ-linolenic acid, arachidonic acid, α-linolenic acid, eicosapentaenoicacid, and docosahexaenoic acid) were formed into complexes with 250 μMfatty-acid-free bovine serum albumin, and were added at a concentrationof 200 μM, respectively. Twenty-four hours later, the individualcultures were washed with PBS and subsequent to treatment with tripsin,were peeled off from Culture dishes. Those cultures were separatelysuspended in portions of HBSS which contained Nile Red (100 ng/mL).Subsequent to incubation at room temperature for 5 minutes or longer,FACS analysis was conducted. From average fluorescence intensities,synthesized quantities of triacylglycerols were measured. The resultsare shown in Table 5. TABLE 5 Fatty acid Fluorescence intensity Linoleicacid ω 6 100 γ-Linolenic acid 70 Arachidonic acid 87 Oleic acid ω 9 191α-Linolenic acid ω 3 42 Eicosapentaenoic acid 52 Docosahexaenoic acid 49Relative values of average fluorescence intensities when the averagefluorescence intensity of linoleic acid was supposed to be 100.

As a result, among these fatty acids, those most hardly synthesized intotriacylglycerols were the ω3 fatty acids (α-linolenic acid,eicosapentaenoic acid and docosahexaenoic acid), followed by the ω6fatty acids (linoleic acid, γ-linolenic acid and arachidonic acid). Theω9 fatty acid (oleic acid) was most liable to synthesis into thecorresponding triacylglycerol among these fatty acids.

It has been found that a difference arises in the amount of synthesizedtriacylglycerols depending on the kinds of fatty acids which exist inthe epithelial cells of the small intestine.

Example 4 Effect of Diacylglycerols on Energy Metabolism

Male rats of an SD strain (7 weeks old) (Japan Charles River Inc.) wereprovided, and they were provisionally reared for 3 days. Using a 10%diacylglycerol (DAG) added feed (DAG group: n=6) or a 10%triacylglycerol (TAG) added feed (TAG group: n=7), they were thensubjected for 1 week to two-meals-a-day rearing (eating time: 8:00 to9:00, 21:00 to 22:00) in which the feed was given twice a day. Withrespect to the rats which had learned the timing of feed ingestion asdescribed above, an expiration analysis was conducted for 22 hours(19:00 to 17:00) Using “Oxymax v. 5. 61” (trade name; manufactured byColumbus Instruments), the expiration analysis was conducted to measurethe volume of oxygen consumed by the rats and the volume of carbondioxide excreted by the rats. TABLE 6 Compositions of Rat Feeds TAG feedgroup DAG feed group (%) (%) TAG 10 0 DAG 0 10 Casein 20 20 Cellulose8.1 8.1 Mineral mix 4 4 Vitamin mix 2.2 2.2 Potato starch 55.5 55.5L-methionine 0.2 0.2 Total 100.0 100.0DAG: Oil or fat composition BTAG: Soybean oil

As a result, the DAG group was significantly high in the total energyconsumption over 22 hours than the TAG group (p<0.05 vs the TAG group)although there was no difference between the DAG group and the TAG groupin the amount of the ingested feed during the 1-week pre-rearing and themeasurement of the energy metabolism volumes (22 hours). Especially inan inactive, bright period (7:00 to 17:00), the total energy consumptionsignificantly increased (p<0.001 vs the TAG group) (FIG. 1). As theingestion of diacylglycerols led to higher energy consumption than thatof triacylglycerols, it was suggested that diacylglycerols are moreeasily burnable as energy. Diet (meal) induced thermogenesis (DIT) wasenhanced especially after the ingestion of diacylglycerols.

Example 5 Effect of Diacylglycerols on the Burning of Dietary Lipids

Subsequent to rearing for 4 weeks with a feed which containeddiacylglycerols (DAG) at a concentration of 30% (Table 7), mice (CLEAJapan, Inc.) (n=8 per group) were fasted for 14 hours. Subsequently,triacylglycerols (TAG) which contained 28% of tripalmitin labeled with¹³C at the 1-position thereof were administered as an emulsion, thecomposition of which is shown in Table 8, once by using a feeding tube(“Safeed Fr. 3.5”, trade name; product of Terumo Corporation). As acontrol, mice (n=8) which had been reared for 4 weeks with a feedcontaining 30% of TAG of the same fatty acid composition were fasted andadministered likewise. After the administration of the emulsion, themice in the respective groups were separately placed in metabolic cages[“METABOLICA” (trade mark), manufactured by Sugiyama-Genki Iriki Co.,Ltd.)], and their expirations were caused to be absorbed in portions ofa 5 N aqueous solution of sodium hydroxide before the initiation of theexperiment and from the 0^(th) hour to 10^(th) hour, from the 10^(th)hour to 24^(th) hour and from the 24^(th) hour to 33^(rd) hours, allafter the administration of the emulsion. During the 33 hours for thesampling of the expirations, the DAG feed (the TAG feed for the control)and drink water were given ad libitum. The CO₂ in each expirationsample, which was collected in the aqueous sodium hydroxide solution,was caused to precipitate as CaCO₃ by using calcium chloride andammonium chloride. The amount of ¹³C contained in the CaCO₃ wasdetermined using a mass spectrometer (“ANCA-SL”, trade name;manufactured by PDZ Europe Ltd.). In this manner, variations in thelevel of ¹³C—CO₂ in the expiration from the mice in each group wereinvestigated. Further, mice were similarly reared, and were likewiseorally administered with triacylglycerols which contained[1-¹³C]-tripalmitin labeled with ¹³C at the 1-position thereof. Thosemice were then fed with the same test feeds, respectively, and weresacrificed 24 hours later or 32 hours later to collect their epididymalfat tissues and mesenteric fat tissues. From each of those organs,lipids were extracted with a 1:2 v/v mixed solvent of methanol andchloroform. The amount of ¹³C in the whole lipids was quantitated, andwas presented as a percent accumulation based on the administeredamount. TABLE 7 Compositions of Mouse Feeds TAG feed group (%) DAG feedgroup (%) TAG 30 0 DAG 0 30 Sucrose 13 13 Cellulose 4 4 Mineral mix 3.53.5 Vitamin mix 1 1 Potato starch 48.5 48.5 Total 100.0 100.0DAG: Oil or fat composition B,TAG: Soybean oil

TABLE 8 Composition of emulsion (%) Mixed lipids 5 Lecithin 0.2 Albumin2 Distilled water 92.8 Total 100.0Mixed lipids (with 28% of ¹³C-labeled tripalmitin)

As a result, in each of the DAG administered group and the controlgroup, ¹³C—CO₂ derived from the single-administered lipids was releasedinto the expiration from the 0^(th) hour to 10^(th) hour after theadministration of the labeled lipids, and after the 10^(th) hour, itsconcentration dropped (FIG. 2). Further, the amounts of ¹³C—CO₂ in theexpirations from the oth hour to 10^(th) hour and from the 24^(th) hourto 33^(rd) hour were significantly higher in the TAG feed group than inthe DAG feed group although there was no difference in the amountingested during the expiration sampling time between the DAG group andthe TAG group. This clearly indicates that long-term ingestion ofdiacylglycerols promotes oxidative degradation (burning) of TAG ingestedfrom other feeds. As body fat accumulation suppressing effect ofdiacylglycerols, energy releasing effect associated with burning ofdietary lipids subsequent to ingestion of diacylglycerols wasdemonstrated.

In each of the DAG feed group and the TAG feed group, the percentaccumulation of ¹³C in fat was higher in the mesenteric fat (B) than inthe epididymal fat (A). On the 33^(rd) hour after the administration ofthe lipids, the percent accumulations of ¹³C in both the epididymal fatand mesenteric fat were both found to be significantly low values in theDAG feed group than in the TAG feed group (FIG. 3).

From the foregoing, diacylglycerols have been found to be equipped witheffect that, when ingested, they promote burning not onlydiacylglycerols but also other dietary lipids to excrete them as anexpiration and hence, to suppress their accumulation as body fat.

Example 6 Remnant-Like Lipoprotein (RLP) Level Lowering Effect

The groups of volunteers relatively high in serum triacylglycerol level,each consisting of 8 adult male and female volunteers, used theabove-described oil or fat compositions AtoE, respectively, for onemonth (average ingestion: 10 g/day) in place of edible oils which theyhad used daily. Blood samples were drawn both before and after the useof the oil or fat compositions A to E, and their serum RLP levels weremeasured (Table 9).

The serum RLP levels were each quantitated based on the amount ofcholesterol in a fraction which had been obtained by conductingfractionation with an anti-apo B-100-anti-apo A1 monoclonal antibodyaffinity mixed gel. TABLE 9 Oil or fat composition c/(t + S) RLP levelInvention A 20.1 83.1 B 11.3 86.3 C 6.2 92.1 D NT 90.3 ComparativeSoybean oil 5.1 103.8Shown in terms of relative value when the initial values were supposedto be 100.NT: Not tested.

As the ingestion of the diacylglycerol-containing oil or fatcompositions A to E was able to lower the serum RLP levels,diacylglycerols can prevent diseases such as angina pectoris andmyocardial infarction.

Example 7 Serum Leptin Lowering Effect

The groups of volunteers high in body mass index, each consisting of 5male volunteers and 9 female volunteers, used the above-described oil orfat compositions A to D, respectively, for one month (average ingestion:10 g/day) in place of edible oils which they had used daily. Bloodsamples were drawn both before and after the use of the oil or fatcompositions A to D, and their serum leptin levels were measured (Table10). The leptin levels were quantitated by the method which performs ameasurement by using an antibody to human leptin [Clin. Chem., 42, 942(1996)]. TABLE 10 Relative serum Oil or fat composition leptin levelInvention A 82.5 B 85.2 C 92.0 D 90.1 Comparative Soybean oil 105.8Shown in terms of relative value when the serum leptin levels before theingestion were supposed to be 100.

The volunteers who ingested the oil or fat composition A were found fromCT scan images of their umbilical region that, as the serum leptin levellowered to 82.5% compared with the serum leptin level before thedigestion (which was supposed to be 100), the subcutaneous fat area andvisceral fat area dropped to 9.3.9% and 94.4%, respectively, and at thesame time, the serum triacylglycerol level also dropped to 89.0%.

The oil or fat compositions A to D were all excellent in serum leptinlevel lowering effect.

Example 8 Blood Sugar Level Lowering Effect

(1) Preparation of Diacylglycerol-Containing Oils/Fats

(1)-1

A high-DHA oil (“DHA-45”, trade name; product of MARUHA CORPORATION)(200 parts by weight) and glycerol (10 parts by weight) were mixed.Subsequent to further mixing of an alkali catalyst (sodium methoxide,CH₃ONa) (0.6 part by weight), an a transesterification reaction wasconducted under reduced pressure (0.133 kPa) at 100° C. for 4 hours. Bychromatography on a silica gel column, fractionation of individualcomponents was then conducted. Triacylglycerols (10.3 parts by weight),diacylglycerols (87.4 parts by weight), monoacylglycerols (1.9 parts byweight) and polymerized acylglycerol products (0.4 part by weight) werethen mixed to prepare an oil or fat composition F.

(1)-2

Linseed oil (“SCAN-OIL”, trade mark; importer: NIHON SHOJI K.K.) (180parts by weight) and glycerol (12 parts by weight) were mixed. Followingthe procedure of the preparation (1)-1, a transesterification reactionand fractionation of individual components were conducted.Triacylglycerols (36.8 parts by weight), diacylglycerols (61.3 parts byweight), monoacylglycerols (0.5 part by weight), free fatty acids (0.8part by weight) and polymerized acylglycerol products (0.6 part byweight) were then mixed to prepare an oil or fat composition G.

(1)-3

Perilla oil (140 parts by weight), olive oil (product of WAKO PURECHEMICAL INDUSTRIES, LTD.) (70 parts by weight) and glycerol (20 partsby weight) were mixed. Following the procedure of the preparation (1)-1,a transesterification reaction and fractionation of individualcomponents were conducted. A 100% monoacylglycerol fraction was providedas an oil or fat composition H.

Principal fatty acid compositions of monoacylglycerol and diacylglycerolfractions derived from the thus-obtained oil or fat compositions F, Gand H are shown in Table 11. TABLE 11 Oil or fat composition F G H ω3C18:3 0 60.6 41.3 C20:5 6.7 0 0 C22:6 46.3 0 0 Monoene C16:1 3.4 0 0.2C18:1 10.5 14.5 32.5 C20:1 1.4 0 0.4 C22:1 1.1 0 0 ω6 C18:2 1.3 15.412.9 C18:3 0.7 0 0 Saturated C14:0 2.2 0 0 C16:0 11.3 6.6 6.9 C18:0 2.72.9 2.2Measured by gas chromatography after methylation.(2) Confirmation of Blood Sugar Level Lowering Effect by Using C57BL/6JMice, Diet-Induced Diabetic Models

C57BL/6J mice (male, 7 weeks old) were divided into three groups each ofwhich consisted of 5 mice, and were reared with feeds of thecorresponding compositions shown in Table 12. Thirty days later, bloodsamples were drawn from their abdominal aortas under etherization, andblood sugar levels were measured by “Glucose Test Wako” (trade name;product of WAKO PURE CHEMICAL INDUSTRIES, LTD.). The results are shownin FIG. 4. TABLE 12 Group 1 Group 2 Group 3 High-triacylglycerol oil¹⁾5.0% 30.0% 27.0%  Oil or fat composition F — — 3.0% Casein 20.0%  20.0%20.0%  Cellulose 4.0%  4.0% 4.0% Mineral mix 3.5%  3.5% 3.5% Vitamin mix1.0%  1.0% 1.0% Potato starch 66.5%  41.5% 41.5% ¹⁾Refined soybean oil (product of The Nisshin Oil Mills, Ltd.; this willequally apply hereinafter).

In the group 2 (high lipid load feed (30% TG feed) group), significantrises in blood sugar level were observed compared with the group 1(normal feed (5% TG feed) group). In the group 3 (the oil or fatcomposition F added group), on the other hand, rises in blood sugarlevel were lower compared with the group 1, and blood sugar levels werefound to be lower than those in the group 2.

(3) Confirmation of Blood Sugar Level Lowering Effect by UsingC57BL/KsJ-db/db Mice, Hereditary Diabetic Models

C57BL/KsJ-db/db mice (male, 7 weeks old) were divided into three groupseach of which consisted of 10 mice, and were reared with feeds of thecorresponding compositions shown in Table 13. Two months later, bloodsamples were drawn from their abdominal aortas under etherization, andblood sugar levels were measured by “Glucose Test Wako” (trade name;product of WAKO PURE CHEMICAL INDUSTRIES, LTD.). The results are shownin FIG. 5. TABLE 13 Group 1 Group 2 Group 3 High-triacylglycerol oil¹⁾10.0% 7.0% 6.0% Oil or fat composition G — 3.0% 3.0% Oil or fatcomposition H — — 1.0% Casein 20.0% 20.0%  20.0%  Cellulose  4.0% 4.0%4.0% Mineral mix  3.5% 3.5% 3.5% Vitamin mix  1.0% 1.0% 1.0% Potatostarch 61.5% 61.5%  61.5% ¹⁾As defined in Table 12.

In the group 1 (normal feed (10% TG feed) group), a pronouncedly highblood sugar state was observed. In the groups 2 and 3 in which lipidswere replaced by α-linolenic acid diacylglycerol (the oil composition G:3%) or α-linolenic acid diacylglycerol/monoacylglycerol (the oil or fatcomposition G: 3%+oil or fat composition H: 1%), respectively, on theother hand, significant drops in blood sugar level were observed.

(4) Reduction in Human Blood Sugar Level

Three male volunteers (A, B, C) the fasting blood sugar levels of whichwere 120 mg/dL or higher were directed to ingest the oil or fatcomposition F, which was filled in soft capsules, in an amount of 2 gper day for 3 months without changing their diet life, and then, theirblood sugar levels were measured by “Glucose Test Wako” (trade name;product of WAKO PURE CHEMICAL INDUSTRIES, LTD.). The results are shownin Table 14. As a result, reductions in blood sugar level were observedon all the volunteers. TABLE 14 Initial level 3 months later VolunteerA, 39 years old 123 101 Volunteer B, 45 years old 135 110 Volunteer C,42 years old 142 103 (mg/dL)

Example 9 Insulin Resistance Improving Effect

Normal male volunteers of 24 or higher BMI (or body fat percentage: 23%or higher, slight obesity) were directed to orally ingest the oil or fatcomposition F, which had been formulated into capsules, at a dose of 2 gin a day. Blood insulin levels were measured both before and after theingestion. As a result, the average of blood insulin levels pronouncedlydropped to 12.9 μU/mL after the completion of the ingestion (1 month)(p<0.05), although it was 16.3 μU/mL before the initiation of thedigestion (initial level).

Example 10 Effects of Long-Term Digestion of Diacylglycerols On SerumLipids in Type II Diabetes

A. Testing Method

(1) Test Oils

Employed as test oils were an oil or fat composition I prepared in asimilar manner as the oil or fat composition A by using rapeseed oil anda comparative oil or fat A (TAG) prepared with the same fatty acidcomposition as the oil or fat composition I by mixing rapeseed oil,soybean oil and sunflower oil. The fatty acid compositions of theemployed oil or fat composition I and comparative oil or fat A are shownin Table 15. In the oil or fat composition I, the sum of 1,3-DAG and1,2-DAG (2,3-DAG.) accounted for 86%, and their ratio was 7:3. Besidesthese DAGS, triacylglycerols and monoacylglycerols (MAG) existed inproportions of 13% and 1%, respectively. Incidentally, the heat ofcombustion of the oil or fat composition I as measured by a bombcalorimeter was approximately 9 kcal/g (analyzed by Japan Food ResearchLaboratories, Tokyo, Japan). TABLE 15 Oil or fat composition ComparativeFatty acids I oil or fat A C16 3.16 5.68 C18 1.27 2.23 C18:1 37.49 35.67C18:2 48.27 46.65 C18:3 6.36 6.94 Acylglycerol compositionsTriacylglycerols 12.98 97.78 Diacylglycerols 85.89 1.43Monoacylglycerols 1.06 0.00 Free fatty acids ND NDND: not detected(2) Volunteers and Meal

This study was conducted under full explanation and consent incompliance with the spirit of the Helsinki Declaration. Volunteersconsisted of 24 day patients, who were aged from 38 to 79 and were undercontinued guidance on nutrition (dietotherapy) by Diabetic OutpatientSection, Internal Department, Itami City Hospital. Those diabetics weredivided into two groups, one being the oil or fat composition I groupwhich consisted of 11 diabetics (average age: 61.6±1.9 years old; 4 malediabetics and 7 female diabetics), and the other the comparative oil orfat A group which consisted of 13 diabetics (average age: 54.3±3.6 yearsold; 7 male diabetics and 6 female diabetics).

In the oil or fat composition I group and the comparative oil A group,the oil or fat composition I and the comparative oil or fat A were usedas cooking oils, respectively, in place of oils employed daily. Thevolunteers were each directed to ingest the corresponding cooking oilwith a daily target consumption of 10 g. In each of the groups, theperiod of study was set at 3 months from the initiation of use of thecorresponding cooking oil, and tests were conducted by the double-blindmethod.

Concerning medication to the volunteers, the oil or fat composition Igroup consisted of 1 volunteer medicated using an insulin preparationand an HMG-CoA inhibitor in combination, 1 volunteer medicated with theinsulin preparation, 4 volunteers medicated with a sulfonylureapreparation, 1 volunteer medicated using the sulfonylurea preparationand an α-glucosidase inhibitor in combination, 1 volunteer medicatedwith a biguanide preparation, 1 volunteer medicated using the biguanidepreparation and the sulfonylurea preparation in combination, and 2volunteers without any medication. The comparative oil or fat A group,on the other hand, consisted of 1 volunteer medicated with the HMG-CoAinhibitor, 3 volunteers medicated with the insulin preparation, 2volunteers medicated with the sulfonylurea preparation, 1 volunteermedicated using the biguanide preparation and the sulfonylureapreparation in combination, 1 volunteer medicated with an EPApreparation, and 5 volunteers without any medication.

(3) Physical Measurements and Blood Tests

At intervals of 1 month after initiation of ingestion of the test oils,physical measurements and fasting blood sampling were conducted at thehospital. As physical measurement items, body weight, BMI, waistcircumference and hip circumference were measured. As blood test items,on the other hand, triacylglycerols, total cholesterols (Chol), freefatty acids, LDL-Chol, HDL-Cho, remant-like lipoprotein (RLP)-Chol,lipoprotein (a) [Lp (a)], lipoprotein lipase (LPL) protein quantity,total ketone bodies, acetoacetic acid, 3-hydroxybutyric acid, PAI-1,leptin, insulin, glucose, hemoglobin Alc (HbAlc), apoproteins (ApoA-1,ApoB, ApoC-II, ApoC-III, ApoE), cholesterol ester transfer protein(CETP), and lecithin cholesterol acyltransferase (LCAT) were measured.

(4) Analysis of Serum Lipoproteins by HPLC

An analysis of serum lipoproteins was conducted in accordance with themethod proposed by Usui et al. and making use of a gel filtration column(J. Lipid Res., 43 (5), 805-814, 2002). This method has merits that theoperation is simple and is practically unaffected by the composition andtemperature of an eluent, reproducibility is very high, and serum can beaccurately and quantitatively analyzed in a shorter time without needingit in a large amount.

Serum samples were each diluted with physiological saline, and reservedat 5° C. until its analysis for lipoproteins by HPLC.

(5) Statistical Testing Method

Each value so obtained was expressed in terms of mean±standard error (S.E.), while its variation from the corresponding initial value when theinitial value was supposed to be 100% was expressed in terms ofmean±standard error (S. E.) Inter-group comparisons were conducted bytwo-way ANOVA, and levels of significance were tested by Student'st-test. Further, comparisons between the initial value and valuesmeasured at intervals of 1 month after the initiation of ingestion ofeach test oil were conducted by Student's t-test to test the levels ofsignificance.

Upon conducting two-way ANOVA, the intent-to-treat analysis was adoptedfor the data in the test period. B. Results

(1) Ingested Amounts of Test Oils and Physical Measurements

According to observations by attending physicians, neitherdeteriorations in physical conditions nor side effects by the ingestionof the test oil were acknowledged throughout the test period on all thevolunteers in both the oil or fat composition I ingestion group and thecomparative oil or fat A ingestion group. No changes were made to themedication and dosage during the test period. From the data of dietdiaries, the amount of the test oil ingested per day was found to be14.4 ±1.6 g in the oil or fat composition I group and 13.3±1.6 g in thecomparative oil or fat A group. As a body weight change in the thirdmonth, a decrease of 0.4% (0.2 kg) was shown in the oil or fatcomposition I group, while an increase of 0.4% (0.3 kg) was shown in thecomparative oil or fat A group. Concerning the changes in body weightover the three months, two-way ANOVA found no significant differencebetween both groups. In BMI and hipline, no difference was observedbetween both groups. As a waist circumference change in the third month,a decrease of 1.5% (1.5 cm) was shown in the oil or fat composition Igroup, while no change was shown in the comparative oil or fat A group.Concerning the change in body weight over the three months, two-wayANOVA found a significant difference (P=0.02) between both groups. Evenon the volunteers the initial serum glucose levels of which were 110mg/dL or higher, a significant difference (P<0.001) was observed inwaist circumference between both groups.

(2) Blood Test

Among the serum test items, substantial changes were observed intriacylglycerols and HDL-Chol. As a result of two-way ANOVA of thechanges over the three months, the oil or fat composition I group showeda lowering tendency in triacylglycerols and a significant increase(P<0.05) in HDL-Cho in comparison with the comparative oil or fat Agroup. Data of the volunteers the serum glucose levels of which were 110mg/dL or higher were also analyzed. Concerning changes in gluclose,triacylglycerols and plasma PAI-1 over the 3 months, significantdifferences were all observed by two-way ANOVA between both groups (theydropped in the oil or fat composition I group). As to serum ApoA-1 andApoB over the three months, no changes were observed on all thevolunteers and the volunteers, the serum glucose levels of which were110 mg/dL or higher, in both groups. With respect to ApoC-II, ApoC-IIIand ApoE, on the other hand, lowering tendencies were shown in the oilor fat composition I group in comparison with the comparative oil or fatA group. Concerning serum free fatty acids, total ketone bodies,acetoacetic acid, 3-hydroxybutyric acid, HbAlc, insulin, total-Chol,LDL-Chol, RLP-Chol, LP (a), LPL proteins, leptin, CETP and LCAT, nosignificant differences were observed on all the volunteers and thevolunteers, the serum glucose levels of which were 110 mg/dL or higher,in both groups.

(3) Analysis of Serum Lipoproteins by HPLC

Changes in TG and Chol levels in serum lipoprotein fractions obtained atintervals of 1 month after the initiation of the ingestion of the testoils are shown in Tables 16 and 17. Concerning the TG and Chol levels inCM (chylomicron) fractions, no changes were observed. As to the TGlevels in VLDL fractions in the third month, the oil or fat compositionI group indicated a decreasing tendency in comparison with thecomparative oil or fat A group. Even on the volunteers the initial serumglucose levels of which were 110 mg/dL or higher, a significantdifference (P=0.02) was observed in the change over the three months bytwo-way ANOVA between both groups. With respect to changes in the Chollevels in HDL fractions over the 3 months, all the volunteers and thevolunteers, the serum glucose levels of which were 110 mg/dL or higher,showed increasing tendencies in the oil or fat composition group I, butno significant differences were observed between the oil or fatcomposition group I and the comparative oil or fat A group. Concerningchanges over three months in the TG levels in LDL fractions and smalldense LDL fractions obtained from all the volunteers, significantdifferences were observed by two-way ANOVA in both fractions betweenboth groups. Even on the volunteers the serum glucose levels of whichwere 110 mg/dL or higher, the TG levels in the LDL fractions and smalldense LDL fractions in the third month were observed to developsignificant decreases (P<0.05) in the oil or fat composition I group incomparison with the comparative oil or fat A group. TABLE 16 Changes inTG and Chol Levels in Serum Lipoprotein Fractions by HPLC method Oil orfat composition I group (n = 11) Comparative oil or fat A group (n = 13)Two-way 0 month 1 month 2 months 3 months 0 month 1 month 2 months 3months ANOVA CM TG^(a) % 100 141.0 ± 515.6 ±  255.3 ± 105.6 100   123.0± 35.9 245.2 ± 58.5  480.8 ± 309.1 48.2 239.8 (mg/dL) (0.77 ±    (0.70 ± (0.82 ±  (0.73 ± 0.43)    (0.47 ± 0.13)    (0.56 ± 0.27)  (0.76 ± 0.23) (0.59 ± 0.16) 0.37) 0.30) 0.28) Chol^(b) % 100 176.9 ± 716.5 ± 151.8 ±63.8   100   105.3 ± 35.7  378.7 ± 182.1 178.9 ± 63.7   72.6 445.1(mg/dL) (0.27 ±    (0.32 ±  (0.37 ±  (0.30 ± 0.16)    (0.13 ± 0.04)   (0.19 ± 0.08)  (0.23 ± 0.06)  (0.16 ± 0.04) 0.15) 0.17) 0.17) VLDL TG% 100 123.9 ± 121.1 ± 94.5 ± 8.8   100 117.7 ± 8.9  123.9 ± 17.3 130.1 ±15.3   16.0 17.9 (mg/dL) (115.8 ±   (127.5 ±   (111.2 ±   (100.1 ±23.8)      (85.6 ± 21.0)   (117.7 ± 36.8)  (92.2 ± 19.9)  (98.1 ± 19.0)28.2) 25.4) 21.6) Chol % 100 120.6 ± 123.4 ± 102.5 ± 6.9    100 137.0 ±9.8  123.7 ± 6.8  107.2 ± 8.8    10.6 7.8 (mg/dL) (50.0 ±    (58.0 ± (58.8 ± (51.0 ± 6.1)      (41.2 ± 2.5)    (55.2 ± 3.9) (49.9 ± 3.0)(43.7 ± 4.5)   5.1) 5.2) 4.1) LDL TG % 100  91.4 ±  58.7 ±   84.1 ±7.1^(#)  100   76.5 ± 6.2  93.5 ± 18.8 111.4 ± 10.8   Interaction 5.35.1^(###) (P = 0.03) (mg/dL) (85.3 ±    (76.7 ±  (47.8 ± (67.7 ± 8.6)     (60.5 ± 9.5)    (43.8 ± 7.4) (43.8 ± 4.5) (60.2 ± 7.0)   11.4) 10.8)6.9) Chol % 100  95.8 ±  92.7 ± 111.6 ± 7.2    100   85.8 ± 5.0 104.8 ±9.0  114.8 ± 8.6    4.8 5.6 (mg/dL) (114.3 ±   (108.0 ±   (103.5 ±  (125.8 ± 11.8)     (106.8 ± 8.0)   (88.7 ± 6.3) (106.6 ± 8.4)  (118.4 ±8.8)    9.5) 9.4) 8.6)^(a)TG: Triacylglycerol^(b)Chol: CholesterolValues are mean ± S.E.Parenthesized values are actual measurements.^(#),^(###)P < 0.05, P < 0.001 vs the initial value (0 month).

TABLE 17 Changes in TG and Chol Levels in Serum Lipoprotein Fractions byHPLC method Oil or fat composition I group (n = 11) Comparative oil orfat A group (n = 13) Two-way 0 month 1 month 2 months 3 months 0 month 1month 2 months 3 months ANOVA HDL TG^(a) % 100 108.3 ± 7.4  92.3 ± 8.0100.4 ± 10.7 100 103.1 ± 7.9  105.8 ± 6.7  106.9 ± 7.6 (mg/dL) (25.0 ±  (26.2 ± 3.8) (21.6 ± 3.7) (22.5 ± 2.7) (21.3 ± 1.8)   (22.7 ± 3.5)(21.8 ± 1.7)  (21.8 ± 1.6) 4.0) Chol^(b) % 100 102.1 ± 4.1  105.1 ± 5.2  116.6 ± 5.1^(##) 100 104.4 ± 4.1  112.1 ± 3.9  112.6 ± 5.6 (mg/dL)(39.0 ±   (39.7 ± 2.1) (40.7 ± 2.2) (45.5 ± 2.8) (44.8 ± 2.7)   (46.7 ±3.4) (49.5 ± 2.6)  (50.2 ± 3.6) 1.5) Small dense LDL TG % 100   97.1 ±6.3   65.8 ± 6.1^(###)   80.6 ± 7.9^(#),* 100   83.2 ± 8.0  94.6 ± 16.6106.6 ± 8.9 Interaction (P = 0.046) (mg/dL) (21.9 ±   (20.4 ± 3.0) (13.8± 2.4) (16.5 ± 2.6) (15.0 ± 2.3)   (12.6 ± 2.8) (11.8 ± 1.4)  (14.6 ±1.8) 3.4) Chol % 100   96.4 ± 4.5 108.1 ± 3.6  117.4 ± 7.4  100   83.2 ±5.1 113.8 ± 11.8 125.8 ± 9.4 (mg/dL) (32.4 ±   (30.7 ± 2.4) (35.2 ± 3.4)(38.2 ± 4.6) (30.1 ± 2.4)   (24.3 ± 1.8) (33.1 ± 3.5)  (37.5 ± 3.9) 2.7)^(a)TG: Triacylglycerol^(b)Chol: CholesterolValues are mean ± S.E.Parenthesized values are actual measurements.^(#),^(##),^(###)P < 0.05, P < 0.01, P < 0.001 vs the initial value (0month).*P < 0.05 vs the comparative oil or fat A group(4) Evaluation of HOMA-R Values

Values of HOMA-R, an index of insulin resistance, were evaluated. HOMA-R(homeostasis model assessment insulin resistance index) is calculatedby: Starving sugar blood level (mg/dL) x Starving insulin level(μU/mL)±405. HOMA-R is an index of insulin resistance, and its normalvalue is smaller than 2. A value of 4 or greater is interpreted toindicate a high degree of insulin resistance. As a result, HOMA-Rincreased by 39% 3 months later in the comparative oil or fat A group,while HOMA-R decreased by 19% in the oil or fat composition I group.

As demonstrated above, it has been found that by administration of aneffective amount of a diacylglycerol to a diabetic patient, insulinresistance improving effect, HOMA-R lowering effect, lipid metabolismimproving effect, and improving effects for the triacylglycerol leveland/or cholesterol level in serum lipoprotein fraction are exhibited tomake improvements in various diabetes-associated symptoms.

It has also become evident that dietary therapy in which adiacylglycerol is administered in an effective amount is effective fordiabetics. This indicates that diacylglycerol-containing medical foodsfor diabetic patients are useful.

Example 11 Effects of Long-Term Digestion of Diacylglycerols onGlycohemoglobin Alc (HbAlc) in Type II Diabetics

(1) Test Oils

Similarly to Example 10, the oil or fat composition I and thecomparative oil or fat A (TAG) were used.

(2) Volunteers and Meal

This study was conducted under full explanation and consent incompliance with the spirit of the Helsinki Declaration. Selected asvolunteers were 16 day patients, who were under continued guidance onnutrition (dietary therapy) by Diabetic Outpatient Section, InternalDepartment, Itami City Hospital. Those diabetics were divided into twogroups, one being the oil or fat composition I group which consisted of8 diabetics (average age: 56.8±7.3 years old; 3 male diabetics and 5female diabetics) and the other the comparative oil or fat A group whichconsisted of 8 diabetics (average age: 54.1±18.8 years old; 4 malediabetics and 4 female diabetics).

As in Example 10, the oil or fat composition I and the comparative oilor fat A were used as cooking oils, respectively, in place of cookingoils employed daily. The volunteers were each directed to ingest thecorresponding cooking oil with a daily target consumption of 10 g. Ineach of the groups, the period of study was set at 3 months from theinitiation of use of the corresponding cooking oil, and tests wereconducted by the double-blind method.

Concerning medication to the volunteers, the oil or fat composition Igroup consisted of 1 volunteer medicated with the insulin preparation, 1volunteer medicated with the sulfonylurea preparation, 1 volunteermedicated with the α-glucosidase inhibitor, and 2 volunteers without anymedication. The comparative oil or fat A group, on the other hand,consisted of 1 volunteer medicated with the sulfonylurea preparation, 1volunteer medicated with the α-glucosidase inhibitor, and 6 volunteerswithout any medication.

(3) Evaluation of HbAlc

At intervals of 1 month after the initiation of the ingestion of thetest oils, physical measurements and fasting blood sampling wereconducted at the hospital. Values of blood HbAlc, one of principaldiabetes markers, were measured by HPLC method (Clin. Chem., 30, 1746,1984).

As a result, the HbAlc value (%, mean±S. D.) significantly dropped from6.41±1.15 (upon initiation of the test) to 5.79±0.85 (3 months after) inthe oil or fat composition I group. This value (3 months after) fallswithin the normal value range (4.3 to 5.8%) specified by Japan DiabetesSociety (J. Japan Diab. Soc., 37, 855, 1994). In the comparative oil orfat A group, on the other hand, the HbAlc value was 6.88±0.53 (uponinitiation of the test) and 6.65±0.73 (3 months after), and did notchange substantially.

As demonstrated above, it has become evident that the HbAlc value isimproved by ingesting the oil or fat composition I according to thepresent invention.

1. A method for activating lipid catabolism in the small intestineepithelium, which comprises administering an effective amount of adiacylglycerol.
 2. The method according to claim 1, wherein 15 to 90 wt.% of constituent fatty acids of said diacylglycerol comprise ω3unsaturated fatty acids.
 3. The method according to claim 1 or 2,wherein 1,3-diacylglycerols in said diacylglycerol amount to at least 50wt. % of the whole diacylglycerol.
 4. A method for promotingaccumulation of fatty acids into the small intestine epithelium, whichcomprises administering an effective amount of a diacylglycerol.
 5. Themethod according to claim 4, wherein 15 to 90 wt. % of constituent fattyacids of said diacylglycerol comprise ω3 unsaturated fatty acids.
 6. Themethod according to claim 4 or 5, wherein 1,3-diacylglycerols in saiddiacylglycerol amount to at least 50 wt. % of the whole diacylglycerol.7. A method for inducing expression of a small intestine lipid metabolicgene, which comprises administering an effective amount of adiacylglycerol.
 8. The method according to claim 7, wherein 15 to 90 wt.% of constituent fatty acids of said diacylglycerol comprise ω3unsaturated fatty acids.
 9. The method according to claim 7 or 8,wherein 1,3-diacylglycerols in said diacylglycerol amount to at least 50wt. % of the whole diacylglycerol.
 10. A method for suppressingsynthesis of a triacylglycerol in the small intestine epithelium, whichcomprises administering an effective amount of a diacylglycerol.
 11. Themethod according to claim 10, wherein 15 to 90 wt. % of constituentfatty acids of said diacylglycerol comprise ω3 unsaturated fatty acids.12. The method according to claim 10 or 11, wherein 1,3-diacylglycerolsin said diacylglycerol amount to at least 50 wt. % of the wholediacylglycerol.
 13. A method for promoting energy consumption, whichcomprises administering an effective amount of a diacylglycerol.
 14. Themethod according to claim 10, wherein 15 to 90 wt. % of constituentfatty acids of said diacylglycerol comprise ω3 unsaturated fatty acids.15. The method according to claim 13 or 14, wherein 1,3-diacylglycerolsin said diacylglycerol amount to at least 50 wt. % of the wholediacylglycerol.
 16. A method for lowering a serum RLP level, whichcomprises administering an effective amount of a diacylglycerol.
 17. Themethod according to claim 16, wherein 15 to 90 wt. % of constituentfatty acids of said diacylglycerol comprise ω3 unsaturated fatty acids.18. The method according to claim 16 or 17, wherein 1,3-diacylglycerolsin said diacylglycerol amount to at least 50 wt. % of the wholediacylglycerol.
 19. A method for lowering a serum leptin level, whichcomprises administering an effective amount of a diacylglycerol.
 20. Themethod according to claim 19, wherein 15 to 90 wt. % of constituentfatty acids of said diacylglycerol comprise ω3 unsaturated fatty acids.21. The method according to claim 19 or 20, wherein 1,3-diacylglycerolsin said diacylglycerol amount to at least 50 wt. % of the wholediacylglycerol. 22-32. (canceled)
 33. A medical food for a diabeticpatient, comprising a diacylglycerol.
 34. A processed oil or fat foodhaving insulin resistance improving effect, comprising a diacylglycerol.